At 10:23 am on 6 June 2011, the ALOHA Cabled Observatory (ACO) saw “first light,” extending power, network communications and timing to a seafloor node and instruments at 4726 m water depth 100 km north of Oahu. Station ALOHA is the field site of the Hawaii Ocean Time-series (HOT) program that has investigated temporal dynamics in biology, physics, and chemistry since 1988. HOT conducts near monthly ship-based sampling and makes continuous observations from moored instruments to document and study climate and ecosystem variability over semi-diurnal to decadal time scales. The cabled observatory system will provide the infrastructure for continuous, interactive ocean sampling enabling new measurements as well as a new mode of ocean observing that integrates ship and cabled observations. The ACO is a prototypical example of a deep observatory system that uses a retired first-generation fiber-optic telecommunications cable. The system was installed using ROV Jason operated from the R/V Kilo Moana. Here we provide an overview of the system and instrumentation, the installation operation, and a sample of initial data. Sensors now connected to the ACO provide live video of the surrounding seafloor, sound from local and distant sources, and measure currents, pressure, temperature, and salinity.